Valence band offsets of Sc_xGa_1−xN/AlN and Sc_xGa_1−xN/GaN heterojunctions

Abstract

The valence band offsets of Sc x Ga 1-x N/AlN heterojunction were measured by X-ray photoelectron spectroscopy (XPS) and were found to increase from 0.42 eV to 0.95 eV as the Sc content x increased from 0 to 0.15. The increase in valence band offset with increasing x is attributed to the corresponding increase in spontaneous polarisation of the wurtzite structure. The Sc x Ga 1-x N/AlN heterojunction is type I, similar to other III-nitride-based heterojunctions. The results also indicated that a type II staggered heterojunction, which can enhance spatial charge separation, could be formed if Sc x Ga 1-x N is grown on GaN.

Effects of substrate self-bias and nitrogen flow rate on non-polar AlN film growth by reactive sputtering

“…Similar polarity dependence in the valence band structure was reported for GaN and InN with a polar hexagonal structure. [41][42][43][44][45] For the valence band spectra of GaN, the P 1 peak is dominant for the Ga face (0001), 45) meaning that Self-AlN and Zero-AlN have Al-face and mixed-face structures, respectively. Consequently, self-bias terminates the Al termination at the AlN surface, which is beneficial for the growth of a GaN layer as GaN template substrates for LED devices.…”

Phase quantification by X-ray photoemission valence band analysis applied to mixed phase TiO2 powders

“…Core line XP spectroscopy can thus give surface specific information on composition, chemical state, as well as in some cases other properties such as plasma energy, 3 plasmon resonance, 4 and heterojunction band offsets. [5][6] However, the energy of core orbitals usually cannot be interpreted in terms of the local and long range structure; core level XPS cannot usually be used to distinguish different structures of the same composition, for example crystalline polymorphs, 7 or amorphous vs crystalline phases, unless, as is the case for diamond and graphite, or carbon based polymers, differences in bonding leads to distinctive energy loss features around the core lines. [8][9][10] In contrast, the valence electrons strongly interact with the neighbouring atoms, and their energy distribution will be influenced by the geometrical surroundings of each atom.…”

Properties of GaN nanowires with ScxGa1−xN insertion

“…and as predicted to occur in Ref. . In addition, an internal electric field discontinuity is likely to exist at the interfaces of the heterostructure due to the spontaneous and piezoelectric polarization mismatch between GaN and Sc x Ga 1− x N along the [0001] direction .…”